a(n) = Sum_{k=0..n} C(n,k)^4*(-1)^k.

Terms

a(0) =1a(1) =0a(2) =-14a(3) =0a(4) =786a(5) =0a(6) =-61340a(7) =0a(8) =5562130a(9) =0a(10) =-549676764a(11) =0a(12) =57440496036a(13) =0a(15) =0a(17) =0a(19) =0a(21) =0a(23) =0a(25) =0a(27) =0a(29) =0